JoeR

Since the internet was created to propagate myth and lore, I don't want to disrupt the dialog here.

My 1st comment is RTFM. :)

Second comment is from the GM HHR Owners Manual:

Gasoline Octane

If your vehicle has the 2.2L L4 engine (VIN Code F),
use regular unleaded gasoline with a posted octane
rating of 87 or higher. If the octane rating is less than 87
you may notice an audible knocking noise when you
drive, commonly referred to as spark knock. If this
occurs, use a gasoline rated at 87 octane or higher as
soon as possible. If you are using gasoline rated at
87 octane or higher and you hear heavy knocking,
your engine needs service.

If your vehicle has the 2.4L L4 engine (VIN Code P),
use premium unleaded gasoline with a posted octane
rating of 91 or higher. You may also use regular
unleaded gasoline rated at 87 octane or higher, but
your vehicle’s acceleration may be slightly reduced,
and you may notice a slight audible knocking noise,
commonly referred to as spark knock. If the octane is
less than 87, you may notice a heavy knocking
noise when you drive. If this occurs, use a gasoline
rated at 87 octane or higher as soon as possible.
Otherwise, you might damage your engine. If you are
using gasoline rated at 87 octane or higher and you hear
heavy knocking, your engine needs service.

teknobunie

wow new members new thoughts, but really this was an OLD post so maybe before posting something again, read the old postings. this has been a issue before and again no body got anywhere then, so why are we reposting these. i am not trying to stomp on amyones toes but really to keep reposting this over and over again. go read all the post you can find on a subject and start there, and do whatever you choose with your gas.

captain howdy

At least this time it wasn't a drawn out technical discussion. The thread was started by a moderator, not someone new. You're kind of right. Last time it was SoCalHHR and snksknr94 going at it, this time it's monster5601 and myself. I should have known better.

snksknr94

SoCal shall we??

Somebody should make one post and sticky it with all this info in it, I find myself reading and reposting the same info quite a bit.

captain howdy

Same here.

SIHHR

I put in the good stuff today. I paid 2.47 got plus in Jersey while in NY its like 2.86 Like SoCal said it was only $2.00 more. Driving home from work I did 31 MPG and AVG speed 63 MPH

captain howdy

Did you feel any extra power in you engine? I have never put less than 93 in so I don't know the HHR feels on regular.

SIHHR

Its hard for me to say. I've only used plus a couple of times. The accleration felt a bit stronger.

captain howdy

That's what I figured would feel different. You answered my question.

SIHHR

Plus gas I would have to say is lasting a bit longer. I'm Avg between 25 to 30 MPG. I drive 28 miles each way to and from work. Last Monday I filled up with Reg and by Friday I was down to a qtr tank. This past Monday I used plus and as of today I have slighly below half right now. Since I reseted the meter's on the DIC. It says AVG speed since Monday is 38 MPH and Gas is 25 MPG. At the rate i'm going I should be able to do around 400 miles on a full tank of gas. Being stopped in Traffic or having the car running without moving does lower those figures.